Conventionally, for example, in such a motor toy as a radio controllable car and the like, a battery receptacle for receiving batteries to be used as a power source has been formed integratedly in a plastic vehicle body and provided with a space which can be covered with an openable lid and which has appropriate configuration enough to receive a given number of the batteries having specific dimensions.
In general, a dry battery is best known as a power battery usable in a motor toy of the above type. However, since the dry battery of disposable type has only a small electric energy, it is worn out in a short time when used for a high performance and high power-consuming motor toy. To this end, a nickel-cadmium battery has recently been used as the power battery of the motor toy.
In the case that the nickel-cadmium battery has almost the same configuration as a conventional dry battery, a given number of the nickel-cadmium batteries can be received without any structural or configurational change in an existing dry battery receptacle. However, upon charging of the battery, a battery charger with specific battery-receiving casing is required. Therefore, the nickel-cadmium battery has such disadvantages that not only a cost of the battery charger is increased but charging operation becomes complicated. In order to overcome the disadvantages, there has been manufactured a packaged nickel-cadmium battery unit package comprising an individual connector and the given number of the nickel-cadmium batteries packaged as one unit which are in internal and electric connection with each other. As a result, the charging operation and the connection between the packaged nickel-cadmium battery unit and the motor toy can be facilitated.
On the other hand, the aforementioned packaged nickel-cadmium battery unit is connected through a specific connector to the motor toy and differs in dimension from a battery casing which receives the necessary number of dry batteries. Therefore, the packaged nickel-cadmium battery unit can not be received in an existing dry battery receptacle. For this reason, upon manufacture of motor toys, the battery receptacle having different sizes should be individually formed depending upon a kind of batteries to be used in the motor toy. Moreover, since the motor toys using general dry batteries are different in a structure of the battery receptacle from those using a packaged nickel-cadmium battery unit, there is no interchangeability between both kinds of the batteries. To this end, one type of batteries usable in a certain motor toy, for instance, a packaged nickel-cadmium battery unit which has an economic advantage is not adaptable to a wide range of other motor toys due to the limited compatibility.